Either way. You can use them as a wash, use them to inoculate the vat - or do both.
I feel that if this is a bloomy or washed rind cheese it may be a waste to put it in the milk (especially if you are making large batches) and spray or wash should be enough. Having said that, some of the yeasts in these may be active in the paste of the cheese and continue to create a small amount of gas and aroma so sometime it may be helpful to put them in the milk too, but there are other yeasts for that, so I use PLA and ARN just for surface treatment.